Science Daily
For decades, scientists have known that the effects of global climate change could have a potentially devastating impact across the globe, but Harvard researchers say there is now evidence that it may also have a dramatic impact on public health.
As reported in a paper published in the July 27 issue of Science, a team of researchers led by James G. Anderson, the Philip S. Weld Professor of Atmospheric Chemistry, are warning that a newly-discovered connection between climate change and depletion of the ozone layer over the U.S. could allow more damaging ultraviolet (UV) radiation to reach the Earth's surface, leading to increased incidence of skin cancer.
In the system described by Anderson and his team, water vapor injected into the stratosphere by powerful thunderstorms converts stable forms of chlorine and bromine into free radicals capable of transforming ozone molecules into oxygen. Recent studies have suggested that the number and intensity of such storms are linked to climate changes, Anderson said, which could in turn lead to increased ozone loss and greater levels of harmful UV radiation reaching the Earth's surface, and potentially higher rates of skin cancer.
"If you were to ask me where this fits into the spectrum of things I worry about, right now it's at the top of the list," Anderson said. "What this research does is connect, for the first time, climate change with ozone depletion, and ozone loss is directly tied to increases in skin cancer incidence, because more ultraviolet radiation is penetrating the atmosphere."
Unfortunately, Anderson said, we don't know how this process will evolve over time.
"We don't know what the development of this has been -- we don't have measurements of this deep convective injection of water into the stratosphere that go back in time," Anderson said.
"But the best guide for the evolution of this is to look at the research that connects climate change with severe storm intensity and frequency, and it's clear that there is a developing scientific case that the addition of carbon dioxide to the atmosphere is increasing climate change, and in turn driving severe storm intensity and frequency."
While it's impossible to know how many skin cancer cases may be related to ozone depletion over the U.S., the link between ozone loss and increased incidence of the disease has been extensively studied, Anderson said.
"There has been a major effort by the medical community to define the relationship between decreases in ozone and the subsequent increases in skin cancer," he said. "The answer is quite clear -- if you multiply the fractional decrease in ozone protection by about three, you get the increase in skin cancer incidence. There are 1 million new skin cancer cases in the U.S. annually -- it's the most common form of cancer, and it's one that's increasing in spite of all the medical research devoted to it."
